1. Field of the Invention
The present invention relates to an image recording device for recording a predetermined number of images on a single recording medium.
2. Description of the Related Art
Medical imaging systems such as CT scanners are widely used to obtain image information about local regions, especially afflicted regions, of human bodies. Images reconstructed from such image information are highly useful because they allow the doctor to get a clear view of the local body regions for diagnostic purpose. Actually, the obtained image information is displayed on a CRT monitor or the like, and the doctor diagnoses the imaged region based on the displayed image. The image information displayed on the CRT monitor may also be recorded on a recording medium such as a heat-sensitive recording medium, for example, which may be stored as a hard copy and subsequently be retrieved for medical diagnosis anytime and anywhere, i.e., without time and space limitations. The image information is represented by an image signal which is generated by an image signal source such as a CT scanner or any of various other suitable imaging systems. The image signal is usually applied as an analog video signal to an image output device such as a thermal printer or the like. In the thermal printer, the analog video signal is converted into thermal printing data which are then recorded on a heat-sensitive recording medium by a thermal head.
In some instances, a plurality of images of body regions in the vicinity of a body region to be recorded for diagnosis should also be simultaneously produced on a single recording medium for higher diagnostic accuracy. The simultaneous recording of plural images on a single recording medium is also advantageous from the standpoint of saving storage space for recording mediums.
One conventional image recording device for recording a plurality of images on a single recording medium includes a frame memory corresponding in size to the recording medium, the frame memory having as many as memory areas as the number of images to be recorded. The image recording device has a single address counter for specifying memory addresses where to store desired image data in the frame memory. After desired image data have been stored at specified memory addresses in the frame memory, desired image data stored in the frame memory are retrieved by specifying corresponding memory addresses using the address counter, and then transferred to a scanning recording unit which may comprise a laser scanner, for recording an image on a photosensitive medium in the scanning recording unit.
In such an image recording device, it is desirable that an image to be reproduced on a recording medium be of high resolution to avoid erroneous medical diagnosis based on the reproduced image. In addition, it is also desirable that image data in a new frame be stored in the frame memory while an image is being recorded on the recording medium, for the purpose of shortening the total period of time required for image recording.
The frame memory of the conventional image recording device has a fixed memory area or capacity allotted for a single image to be recorded on the recording medium. Therefore, if the number of images to be recorded on the recording medium is increased, then a memory capacity available for one image is reduced, and the resolution of the recorded images is also lowered.
Furthermore, since only one address counter is employed in the image recording device, no new image data can be recorded in the frame memory while the stored image data are being read from the frame memory. Therefore, while an image is being printed or recorded, new image data cannot be stored in the frame memory, and hence the time required to record desired images cannot be shortened.
The above drawbacks would be obviated if a plurality of frame memories were employed for a greater memory area, and as many address counters were associated with the respective frame memories. However, such a solution would make the image recording device large in size and expensive to manufacture.